Shelf items are shaded twice

Steps to Reproduce:

1. Set graphics mode to Simple

2. Hold a shelf of any type

3. Compare it with other blocks or items

4. Set graphics mode to fancy

5. Look around and see how the direction affects the shading of the item

Observed Results:
Shelves have additional shading applied to their item models, making them stand out from other items when using simple graphics and appear much darker than they should when using fancy graphics.

Expected Results:
Shelf items are shaded like any other block.

Screenshots/Videos attached: Yes

Notes: The duplicate shading is not even directional, so the front face will always appear way too dark.